Stop-watch mechanism



Sept. 30, 1924. v 1,509,899

D. W. MANN STOP WATCH MECHANISM 3 Sheets-Sheet 1 a 1/ w biifj.

wminm Sept. 30 1924.

D. W. MANN STOP WATCH MECHANISM Filed March 26. 1921 3 Sheets-She 2Sept. 30, 1924. 1,509,899

D. w. MANN STOP WATCH MECHANISM Filed larch 26. 192 3 heets-Sheet 3tion.

Patented Sept. 30, 1924.

UNITED STATES DAVID w. MANN, or LINCOLN, MASSACHUSETTS.

STOP-WATCH MECHANISM.

Application filed March 26, 1921. Serial No. 455,805.

To all whom it may concern:

Be it known that I, DAVID W. MANN, of Lincoln, in the county ofMiddlesex and State of Massachusetts, a citizen of the United States,have invented a new and useful Improvement in Stop-Watch Mechanisin, ofwhich the following is a specifica- My invention is an improvement inmechanism useful in stop watches or the like, and relates moreparticularly to the escapement. In watches of ordinary construction theescapement is controlled by the oscillation of a balance wheel governedby a fiat spiral spring called usually the hairspring. The second handof a watch, therefore, moves over its dial bysmall jumps whose period isthat of an oscillation in one direction of a balance wheel, whichusually occupies one fifth of a second, and the watch can only bestopped at such intervals. Any attempt to increase this rate ofvibration above five per second and so increase the accuracy of the stopwatch in timing is rendered difficult, if not almost impossible, becauseof the friction of pivots, etc.

The purpose of my invention is to make an escapement which is adaptedparticularly for use where it is desired to measure short intervals oftime with more accuracy than is possible by means of an ordinary stopwatch, and for" this purpose I provide a vibratory member which issuitably connected with the escapement and is of such character thatrates of vibration of 24 per second or even higher have been secured.

My invention will be understood by reference to the drawings in which itis shown in its preferred form, together with a portion of the usualworks of a watch or clock showing how my embodiment is connected theretoso as to control the watch movement. These parts being of usualconstruction are not described except so far as may be necessary toexplain my invention. In the drawings the parts are very much enlarged.

Figure 1 is a front view of a stop watch movement embodying my inventionshowing the mechanism at rest, a portion of the face being broken away.

Fig. 2 is a similar view, enlarged, showing the mechanism in operativeposition.

Fig. 3 is a similar view showing a portion of the mechanism after it hasbeen stopped, but before it has been reset or brought to the positionshown in Fig. 1.

Fig. 4 is a side view taken from the left side of Fig. 3.

Fig. 5 is a section on line 55 of Fig. 3 showing the vibratory member inplan.

Figs. 6 and 7 are sections on lines 6-6 and 7-7, respectively, of Fig.5. I

Fig. 8 is an enlarged sectional detail illustrating the hand-settingmechanism.

Fig. 9 is a modification of the hand-setting control.

1 is a cylindrical case comprising base plate 2 and having a threadedopening 3. 4 is a neck through which projects the usual winding arbor 5.6 is the second or measuring hand mounted in the usual way on a centralarbor 7 to be moved over the clock face 8 and to be returned to a zeromark. The clock face may be divided into units of any desired character.The arbor 7 carrying the hand is rotated by mechanism well known toclock makers, and hence need not be described. Such mechanism comprisesthe usual spring which is wound by means of the arbor 5 and the usualmechanism operated thereby.

9 is the escapement wheel of usual form operated from the main spring inthe usual way. 10 is the escapement lever by which the escapement wheelis alternately released and stopped so that it allows a step-by-stepmovement to be imparted to the hand 6. The escapement lever 10 ismounted on an axis 11, the upper bearing for which is part of the topface plate 13. The lower end of the axis 11 sets into a hanger 131 inthe form of an arm attached to the under side of plate 13. The base 2has attached to it a block 15 having a neck 16. The vibratory member 14,which takes the place of the ordinary pendulum mechanism, consists of aplate having a rectangular opening 17 of sufiicient width to receive theneck 16,

which projects through it. The vibratory member 14 is attached to theneck 16 by means of a leaf-spring 18 one end of which is attached to theclock by means of a plate 21 and screws 19, while the other end of thespring is attached to the vibratory member by a plate 22' and screws 20,this arrangement being such that the vibratory member is supported fromthe spring at its centre of gravity.

The vibratory member 14 carries two supports 23, 24 from each of whichprojects a screw 25 carrying threaded weights 26 by which the timing ofthe member 14 may be adjusted. It also carries two pins 2*? and 28, thepin 28 being preferably mounted on support 2- 1. @ne of these pins 27engages the notched end of a sprin impulse lever 29., which is mountedon the axis 11 so that it and the escapement lever will move together.

it is desirable for accurate timing that the impulse lever should be aspring because it permits varying amplitudesoi the vibratory memberabove the i'i'iinimum angle required to unlock the escapeinent and sopermits the vibratory member to take up its natural period of vibrationwith out substantial restraint from the escapement.

The lever 29 lies parallel with the vibratory member acting as theoperative connection between the escaoeinent lever 10 and the vibratorymember 14. The pin 28 which is mounted on the support 2 forms onemember-o f a stop n'iechanisin the other member of which is a lev 3Opivoted at 31 on top of the plate 13. This lever is of angular shape andhas toe 82 at its end to engage the pin 28 and a heel 33 which when themechanism is at rest engages one off a series of projections on theupper surface of a ratchet wheel mounted on an arbor 3-43; in the plate13. The ratchet is operated by a pawl 36. Thepawl 36 is mounted on theend of a pin 37 carrier. by an armature 38 pivoted at 3 9 to asi'iitable Frame and operated by means of an electromagnet 40. The plate13 is slotted as at 41 0 allow the mechanism which operates the )awl 36to be moved by the armature to lo its work. Thus when the electromagne"is energized. the ratchet wil one tooth. The projections 3 l are mountedabout the face 01 the ratche to form slots or recesses, these slots 1' ievery third tooth oi the rat Let each third movement of the ratchet oypawl 36 the heel 3-3 of the lever pulled into the registering slo spring332 one end of which is attac ied to the lever 30 and the other to the13. Normally the heel rests agains; edge of one of the projections iimethe toe ei gages the pin holds the vibratory member statior igure 1shows the mechanism at rest and l 2 shows these parts in oaerativeposition, the vibratory member being actuated brough the escapcment. llhen the parts are in the position shown in Fig. l the vilu'atoi'y memberis held against motion by means of the contact between the toe 32 andthe pin 28. T11 Fig. 2 where the electro magnethas been energized andhas caused the pawl to turn the ratchet one tooth and the heel has beenpulled into the slot bei i n two of the projections 381 by means 0i itscontrolling spring 332, the toe of the lever 30 has been moved a vayfrom the pin 28 so that the vibratory member is free to vibrate. At thenext movement of the ratchet by the pawl 36 one of the projections 221pushes under the h el of the lever 30 so that the heel rests upon it asin Fig. 3.

The projections 3-31 on the ratchet 35 serve also to operate thehand-setting lever 42. This lever is pivoted at i land is con trolled bya spring 413 which tends to pull its outer pointed end 45' against theheartshaped cam 46 on the arbor 'i' carrying the hand 6, the cam and thehand being arranged in predetermined position and held togetherpreferably described as below so that when the parts are in the positionshown in Fig. l the hand points to zero. lt will be see from 2 that thehand has been moved away from zero and the setting member has beencarried with it. The stop ping of the clock is due to the second impulseof the electromagnet by which the ratchet is again pushed one tooth andthe lever 30 rides again aga' st the projection 331 on the ratchet thusbringing the toe 32 of the ever 30 into engagement again with the pin 2The lever 4-2 is operated in the same way. l't has a linger 461 whichits spring holds against the )eriphery of the projections 331 on theratchet and the first movement of the pawl which sets the parts inoperation by moving the ratchet, throws the finger on the lever 42 outfrom its normal position between two 01" the projections 33]. onto thetop of one of these projections. here the leversetsas shown in Figs. 2and 0 while the clock is in operation aid until after the movement ofthe ratchet which the clock. The energizing of the elec trom gnet for athird time causes the ratchet to turn so that the falls between theprojections on the ratchet and the end 4-5 of the lever strikes theheart-shaped member 46 and noves it until the point of the lever 4:2falls into the recess in the setting member at which time the hand willpointto zero. is a spring pawl to restrain the movement 01 the ratchet.

l prefer to provide means now to be (e scribed "for causing; the cam 46and the h nd 6 to rotate with the arbor without slipping; when the watchis in us For this para s: l have provided mechanism which will beunderstood from Fig. 8. Thehand (5 is mounted on a sleeve 160 on theshaft 7 and wider a washer 700 held in place on the shaft by a pin 701.The settingcam 16 is also mounted on the sleeve 4:60 in the usual way.Instead of the light spring usually employed in devices of this sort forcausing the sleeve carrying the hand to rotate with t e shaft, a clutchTl is provided which is held in contact with the sleeve 460 by a spring72 which by pressing at its lower extremity on a washer 73 pushes theclutch 71 against the sleeve 460 with sufiicient pressure as to cause itto rotate with the shaft 7 without slipping.

To reset the hand when the clock is stopped a lever 74 is pivoted at 7 5on the plate 13. One end is forked to ride over the pin 76 on the underside of lever 42. The lever 74 carries a wedge piece 77 shaped to engagea corresponding wedge or conical surface on the upper side of the clutch71, this arrangement being such that as the setting lever 42 is movedinto engagement with the setting member or cam 46, the wedge piece 77 ismoved into engagement with the clutch 71 and depresses it against thespring 72 so as to release the setting member and hand, thus allowingthe setting member and the sleeve 461 carrying the hand 6, which comesin contact with it, to move together when struck by the end of the lever42.

While the arrangement of the spring 43 is for controlling the lever 42,under ordinary circumstances I prefer the construction shown in Fig. 9where the spring 43 connects the lever 42 with one arm of a bell cranklever 431 pivoted at 432 on the plate 13. The bell crank has a pin 433at the endof its other arm which engages the holding pawl 471 whichdiffers from the holding pawl 47 in the other views by being mounted ona very thin piece of metal of sufiicient strength only to support it. InFig. 1, etc., it will be seen that the effort required of theelectromagnet in starting the clock is greater than that required instopping it or in setting it back to the zero point, this conditionbeing caused by the fact that more power is required to lift theprojection 461 on lever 42 from between the projections 331 on ratchetwheel 35 than is required when the projection 461 rides on theprojections 331. From Fig. 9 it will be seen that these differences ineffort are equalized by the varying pressure of pin 433 against the pawl471, these differences in pressure being caused by the action of thespring 43 against the end of the bell crank lever 431.

The operation of the device will be understood it is believed from theabove description. In the circuit of the electromagnet is a circuitcloser adapted to close the circuit momentarily to attract the armatureand operate the ratchet 35. Upon the position of the ratchet 35 dependsthe operation of the stop watch. Energizing'the electromagnet 40attracts its armature 38 which causes the pawl 36 to move the ratchet 35one tooth. If the parts are in their normal stopped position as shown inFig. 1 an electrical impulse in the electromagnet causes the pawl 36 tomove its ratchet 35 one tooth which brings one of the slots betweentheprojections 331 in register with the heel 33 of the lever 30 so thatthe heel will be drawn into the slots by the spring 332 thus separatingthe toe 32 and the pin 28, and allowing the escapement to operate thevibrator. This situation continues until the next impulse is given tothe armature to move the ratchet another tooth which causes the heel 33of the lever 30 to be pushed out of the slot so that it rests againstone ed e of the next projection and its toe is pushed against the pin 28and stops the movement of the vibrator and the watch. The next impulseof the armature pushes the ratchet another tooth so that it passes incontact with the heel 33 until the parts come again into the positionshown in Fig. 1 ready to have this cycle of opera tion repeated.

During this time the projections on the other side of the ratchet areperforming similar operations in connection with hand-setting mechanism.The finger 461 on the lever 42 in this case normally lies in one of theslots between the projections 331. At the first movement of the ratchetthe finger 461 is thrown out of the slot and rests against an adjacentprojection during the movement of the ratchet. At the third movement ofthe ratchet the lever 42 is reset and is in position to reset the hand 6to zero because of its bearing on the heart-shaped member 45. The lever42 also operates the hand clutch 71 as above described at the same time.The novelty of its construction and operation is due mainly to theconstruction and operation of the vibratory member which, because of thespring connection between the vibratory member and its support, doesaway with pivots and other devices which might produce friction, andthus allows an increase in the rate of vibration of the vibratory memberwhich permits of very accurate measurement of short intervals of time.

I prefer to use a flat or leaf spring as part of the mounting for thevibratory member as it lends itself particularly well to they purpose.Other embodiments of my invention will occur to those skilled in the artWhat I claim as my invention is 1. In an escapement mechanism, astationary member, a. spring mounted thereon, a vibratory member mountedbetween its ends on said spring, an escapement lever, and meansconnecting said escapement lever and said vibratory member whereby saidvibratory member will be vibrated.

21 In an escapement mechanism, a stationary member, a spring mountedthereon, a

vibratory member mounted on said spring, I

a flexible escapement lever, and means connecting said flexibleescapement lever and 1011 211? mem it comprising a vibratory member anda stationary attached to em escapoment lever and connections lJQ'JWGGlIsaid e capenient and 1 said worst 2351 m mber whereby said vibratorymember will be vibrated.

5. ln an escap men-5 mechanism a stationary member, a li. springmounted. tl ereon, a vibratory member mounted between its ends on saidleai spring, and means for operating sad vibr ory membe 6. In aneseapemer t niechai ary nember, a leai s pring mount a vibntory membermounted ends on said leaf sprinv and operating said j a vibratory memberprovidec jnstable means whereby the timing of its vibrations may beadjusted.

7. in an escapement meoln .i 1 ary member, a leaf sln'inn mountedenereon, a vibratory member monnted on said leaf spring, and means foroperating said vibratory member, in combination with a stop rsoaeeemechanism comprising a springeontrolled lever, normally restraining saidvibratory member from movement, and means for disengaging said stoplever irom said vibratory member, said stop lever having a projectionand said last-named means comprising a ratchet having separatedprojections, each adapted to engage the projection on said lever andmeans for turning said ratchet,

whereby the projection on said stop lever H l r in spring between tieprojections on c 1g an electron'iagnet, a

a i i be operated thereby and bearing projections on its face, saidspring-controile being shaped to move between said projections oragainst them according to the relative location of said projections andsaid lever.

DAVID W. MANN.

